The Absolute Effect / Evidence / NSABP B-04
Breast Cancer · Surgical Oncology · Locoregional Disease

NSABP B-04

Clinical question

Does radical mastectomy improve long-term survival compared with less extensive breast and axillary surgery in operable breast cancer?

Trial context
Population
1,665 women with operable breast cancer; clinically node-negative and node-positive cohorts
Intervention
Total mastectomy without axillary dissection vs radical mastectomy
Key endpoint
25-year overall survival
Time horizon / follow-up
25 years
Absolute Effect

What changes for patients?

At 25 years, overall survival among clinically node-negative women was 26% after total mastectomy alone versus 25% after radical mastectomy; HR 1.03 (95% CI 0.87–1.23). There was no significant survival difference. Total mastectomy plus radiation also showed no survival advantage. The major difference was better locoregional control with radiation, not survival.

NNT: Not applicable; no significant survival advantage

Treatment burden / harm

Axillary morbidity

NNH: Not quantifiable from the primary endpoint

Relative effect

HR: 1.03 for total mastectomy vs radical mastectomy in node-negative patients

95% CI 0.87–1.23; P=.72

Clinical interpretation

NSABP B-04 showed no survival advantage from more extensive radical surgery over less extensive surgery, helping establish that local treatment extent alone does not determine survival.

Primary publication

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Current-practice context · reviewed 14 October 2026

NSABP B-04 is historical evidence that more extensive axillary surgery does not automatically improve survival over less extensive surgery in operable breast cancer. Modern care uses sentinel-node staging and selective axillary treatment, with omission of completion dissection in defined populations; the trial should not be used to bypass contemporary pathological staging, radiotherapy or systemic-therapy decisions.

NSABP B-04 primary/registry source ↗ · Current guideline guidance ↗